Skeleton Keys (or simply Keys) are collectible items in JumpStart Adventures 4th Grade: Haunted Island.
During the game's intro, the keys spill out of Ms. Grunkle's sack while she is on her way to her house, and become scattered throughout the island. The player has to find them by playing activities and earning points. A new key is rewarded for every 5,000 points the player earns. The number of keys the player has is displayed at the bottom right corner of the screen.
The keys are then used to enter Ms. Grunkle's house. Each door has five locks that must be opened with five keys. All in all, the player needs to collect 25 keys to open all the locks in Ms. Grunkle's house. Thus, the player needs to have a minimum total score of 125,000 points.